It stands for "Brush Only Style Sphere". The principle is simple: Draw a customized sphere in your own style, while also trying to challenge yourself with a new feature / perspective / type of detailing etc.

People can do this on a monthly basis, and after a year put all the drawings together in an improvement table, to see how far they've come with regards to style and quality.

The rules I've thought of are:

- Preferred resolution: 1000 x 1000 pixels;
- Brushes only, magic select tool optional for limiting the effective range of the brush;
- No transforms or layer styles (multiply, screen etc), no dodge / burn brushes, no vector / path usage, no shape tools, use as few layers as possible;
- Challenge is key, a new styling aspect should be practiced on in the case of each image;
- Coloration and customization are completely up to the artist;
- Draw one sphere each month for 12 months;
- After 12 months, organize all the drawings into a sort of improvement table, and submit it for all to see and enjoy :)

Inspired by  LocklearAoi's cat sphere drawing: http://www.furaffinity.net/view/4213373/

I'd say this would have good meme potential, AND it would be useful for tracking the evolution of one's artistic style in a simple fashion. What do you think?